Field
This disclosure relates to an electrolyte additive for a lithium battery, an electrolyte for a lithium battery, and a lithium battery including the electrolyte additive.
Description of the Related Technology
Lithium batteries are used as the driving source for portable electronic devices sources, such as camcorders, mobile phones, and laptop computers. Lithium secondary batteries are rechargeable at high rates and have a high energy density per unit weight of about three times higher than that of conventional lead storage batteries, nickel-cadmium (Ni—Cd) batteries, nickel-hydrogen batteries, and nickel-zinc batteries.
A lithium battery operating at a high driving voltage is incompatible with an aqueous electrolytic solution as it is highly reactive to lithium. For this reason, the lithium batteries mostly use an organic electrolytic solution. The organic electrolytic solution may be prepared by dissolving a lithium salt in an organic solvent. An appropriate organic solvent may be stable at high voltages and may have a high ionic conductivity, a high dielectric constant, and a low viscosity.
When a lithium battery uses a carbonate-based polar, non-aqueous solvent, an irreversible side reaction between an anode and/or a cathode and the electrolytic solution may occur during an initial charging process, and cause excess consumption of charges.
When a carbonate-based polar non-aqueous solvent is used in the lithium battery, the irreversible reaction using an excessive amount of charges may result in side reactions between an anode/cathode and an electrolyte during an initial charging process of the battery.
The irreversible reaction may also form a thick solid electrolyte interface layer (also, referred to as an SEI layer) formed of decomposition products of electrolyte components on the surface of an electrode, which results in an increase in the initial resistance of the lithium battery and a rapid loss in the cycle capacity retention rate. Thus, the cycle lifetime characteristics of the lithium battery may decrease. More specifically, high operation temperature and high operation voltage could result in severe electrolyte decomposition, and as a result can deteriorate the cycle lifetime characteristics of the lithium battery.
Therefore, there is a demand for an organic electrolyte solution with improved stability and cycle lifetime characteristics at high temperatures and high voltages.